To the Editor:
We read with great interest the article titled: “Do we really need closed-suction drainage in total hip arthroplasty? A meta-analysis”, by Zhou et al. [1]. The authors conducted a meta-analysis to determine whether closed-suction drainage is safe and effective in promoting wound healing and reducing blood loss and other complications compared with no drainage in total hip arthroplasty (THA). The conclusions drawn seem questionable because of several apparent flaws in their study.
Firstly, publication language was limited to English in the meta-analysis; therefore, the authors should consider the potential importance of language bias as a limitation, which was not mentioned. We suggest that publication bias be assessed by visual examination using a funnel plot and statistical tests (e.g. Egger’s linear regression test or Begg’s rank correlation test).
Secondly, a study by Hill et al. [2], which was only a conference abstract, was included in their analysis to minimise bias against smaller studies that were not published in full. We do not agree with this inclusion. Obviously, Hill et al. published their prospective randomised controlled trial (RCT) again in 2005 [3]. To strengthen the credibility of Zhou et al.’s meta-analysis, information from Hill et al.’s abstract should be excluded.
Finally, it is incorrect that summary odds ratio (OR) estimate with corresponding 95 % confidence intervals (CIs) were derived by using the method of Mantel–Haenszel (MH) with the assumptions of a random-effects model. However, studies should be combined by using the DerSimonian and Laird random-effects model, which considers both within- and between-study variations.
We agree with the following conclusions by Zhou et al.: closed-suction drainage reduces the requirement for dressing reinforcement but increases the rate of homologous blood transfusion. No significant difference was observed in the incidence of infection, blood loss, changes in haemoglobin and haematocrit, functional assessment or other complications when the drainage group was compared with the no-drainage group. Larger, blinded RCTs with a longer follow-up period are still needed to provide a powerful and rational conclusion regarding the use of drainage after THA.
Acknowledgments
Conflict of interest
None
References
- 1.Zhou X-d, Li J, Xiong Y, Jiang L-f, Li W-j, Li-dong W. Do we really need closed-suction drainage in total hip arthroplasty? A meta-analysis. Int Orth. 2013 doi: 10.1007/s00264-013-2053-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
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